March 18 to 24 is National Wildlife Week. And, this year, we are focusing on the importance of trees to wildlife and water. Our 2013 theme is “branching out for wildlife” and anyone interested in learning about trees, tree planting or wildlife should visit us online. We are often asked why trees are so important for wildlife and water. There are at least five compelling reasons:

Trees consume water and can regulate stream flows
Urban areas experience increasing amounts of paving and land development that convert large areas of spongy natural land to hard surfaces that cannot absorb water. When rain hits paved-over or built-over areas, it runs off directly into storm drains and eventually into area streams and rivers. A hard, fast rain, with no vegetation or natural land to slow it down can hit these water bodies with such speed and force that it will result in flooding and severe erosion problems. Downstream areas such as bays and estuaries can get deadly slugs of sediment and chemical pollution from these run-off surges.

Anyone who has stood under a tree at the beginning of a rain shower (not advisable in lighting storms) knows that tree canopy absorbs falling rain. In urban areas this can reduce water run-off by as much as 10 percent and that can make a huge difference in the speed and erosive force of the rain shower. That is one reason trees are increasingly becoming a standard design feature for automobile parking lots which, left uncovered, are huge run-off generators. These same parking lots also heat up on hot summer days and contribute to spikes in temperatures know as “heat islands.” Tree canopy is an effective coolant in these areas and that is likewise good for local wildlife and water.

Trees also need water to grow and can help consume excess water in urban areas. Urban planners and designers are paying more and attention to filling remaining “plantable” spaces in cities and suburbs with trees. The recent trend of planting areas called “rain gardens” in parking lots and other developed areas that are specifically designed to capture rain water and help it percolate into the ground. This absorption is facilitated by tree planting.

Trees remove pollutants from the air and water
The science is also clear that trees and wooded areas help to filter pollutants out of the environment and can keep air and water cleaner. They cut down on sediment running into streams, rivers and bays and they also absorb chemical pesticides, and heavy metals, such as cadmium, that can be devastating to water quality, fisheries and wildlife.

Trees can serve as anchors to stream-side habitat areas
The term “riparian area” may not be front of mind for most people but such an area is the (usually narrow) zone of stream-side vegetation that follows the stream and occupies the space between the water and dry land. Because of differences in soils and the amount of moisture they hold, these transitional zone have many unique characteristics.

In some farming and dry land regions riparian areas are the only places where trees are found. The trees there are playing an important role by stabilizing soils, cooling the water, dropping food and nutrients into the stream and providing moist environments for a wealth of native plants in the under-story These vegetative zones help to keep streams cleaner and they literally absorb and slow down food waters. In many parts of the nation, such as in the West, wooded riparian areas support as many as 70 percent of local species. They are vitally important to birds, insects, mammals, amphibians and many other creatures and when they are cleared for farming, development or just improved views of the stream, wildlife diversity drops sharply. Likewise, tree planting becomes an important first to restore degraded riparian zones.

Trees provide resting places during migration
Resident wildlife species certainly need trees but they are also important for our migrating visitors. Birds and insect species traveling over great distances need wooded areas to rest and refuel on their long journeys. Central Park in New York City is famous for being an area that attracts an unbelievable diversity of bird species despite being surrounded by skyscrapers and America’s most dense urban environment. One study in the United Kingdom found that even a small area of an acre can be vitally important to migrating species in need of a little rest.

Trees, living and dead, are great for food and habitat
There are several fallen trees right outside the windows of the National Wildlife Federation HQ in Reston, Virginia. In February of this year, a staff meeting was put on pause so we could observe a beautiful pair of pileated woodpeckers driving holes into the logs and feeding on the insects inside. Live trees offer creatures important habitat for sure but dead trees are important too because they provide food, holes and cavities for nests and shelter. In the eastern forests, for example, a combination of shelter and food from living trees such as an abundant acorn crop combined with rotting trees and snags on the forest floor can provide an unbeatable safety net of support to wildlife species throughout the food web.

National Wildlife Federation is honored to be affiliated with National Aquarium. Our reasons for joining forces include the protection of the Chesapeake Bay and other coastal areas. Forested areas, large and small, are vital to that goal!

Join us this year in celebrating National Wildlife Week and supporting nation-wide tree planting programs!